A base station that carries out radio communications with plural pieces of radio equipment is known (for example, refer to Japanese Laid-open Patent Publications No. 2014-150558 and No. 2014-049932, and 3GPP TS 36.300 V10.11.0, “Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA) and Evolved Universal Terrestrial Radio Access Network (E-UTRAN); Overall description; Stage 2 (Release 10),” [online], September 2013, [retrieved on Feb. 2, 2015], Internet <URL:http://www.3gpp.org/ftp/Specs/archive/36_series/36.300/36300-ab0.zip>). For example, the base station carries out communications in accordance with the LTE-Advanced system. LTE is an abbreviation of Long Term Evolution.
The LTE-Advanced system uses a carrier aggregation (CA) technique. In the CA technique, communications are carried out by using plural component carriers (CCs).
For example, the LTE-Advanced system uses up to five CCs. The frequency bandwidth possessed by one CC is at most 20 MHz. Therefore, in the LTE-Advanced system, communications are carried out by using a frequency bandwidth of up to 100 MHz. This can increase the amount of data transmitted per unit time (in other words, communication throughput).